1. Field of the Invention
The present invention relates to stud welding. More specifically, the present invention provides an improved welding stud for a stud welding gun.
2. Description of the Related Art
It has been common practice to attach labels or other information bearing tags to steel bars or other metallic product bundles or objects for identification purposes before their being subjected to further types of processing, such as galvanizing or other treatment, or for shipment. Problems arose if the label was broken away from the object or bundle before or during processing or treatment. One form of label attachment was based on the use of welding studs for that purpose. U.S. Pat. No. 5,565,116, of which Applicant is a named inventor, related to one form of such a welding stud.
With studs of these types, the ability of the stud to remain affixed with the labeled object as a result of contact with another body or component during shipping or handling was a function of the strength of the attachment weld. There were situations where the attachment weld could be weak due to one or more of several factors. For example, when a high-carbon steel content object to receive the stud was at an ambient or unheated temperature at the time the stud was welded, in contrast to a heated state, the resultant weld might not be as strong as it could have been. Further, high alloy steel or high carbon cold application of the stud after fabrication might result in weld zones that have poor or less than normal weld strengths. If the contact force transmitted through the body of the stud when bent was greater than the strength of the attachment weld, the stud became dislodged or broke away from the labeled object. Dislodgment or breakage of the stud was undesirable and contrary to the purpose for which the stud was intended to be used.